@mixin breakpoint($class) {
  @if $class == ltxs {
    @media (max-width: $screen-xs) { @content; }
  }

  @else if $class == xs {
    @media (max-width: $screen-xs-max) { @content; }
  }

  @else if $class == sm {
    @media (min-width: $screen-sm-min) and (max-width: $screen-sm-max) { @content; }
  }

  @else if $class == md {
    @media (min-width: $screen-md-min) and (max-width: $screen-md-max) { @content; }
  }

  @else if $class == lg {
    @media (min-width: $screen-lg-min) { @content; }
  }

  @else {
    @warn "Breakpoint mixin supports: xs, sm, md, lg";
  }
}
